Dense renal papillae: a quantitative study using computed tomography.

The attenuation of the renal papillae has been compared with that of the cortex/outer medulla (COM) in 100 consecutive patients undergoing abdominal computed tomography (CT). In most patients (73%) there were areas within the papillae measuring more than 5 Hounsfield units (HU) higher than the COM. In 11% of the patients this increase in papillary attenuation was even more marked (15 or more HU). Increased papillary attenuation was most marked in patients with newly diagnosed widespread malignancy; it was also common in thin patients and in those who were in-patients. The region of the papilla has been shown to have a slightly higher CT attenuation than the rest of the renal parenchyma and such density seems especially noticeable in sick patients.